UK Omicron infections ?could reach 1m a day by end of December?

Britain's wave of Omicron infections could reach 1m a day by the end of December, the government's most senior public health adviser has warned amid growing calls to limit Christmas gatherings.

Dr Susan Hopkins told MPs on Tuesday the Omicron Covid variant was initially doubling every two to three days in the UK but the pace appeared to have speeded up, driving a surge of disease that risked putting "significant" pressure on the NHS.

While confirmed cases of the variant are being tracked through genomic testing, the number of Omicron infections across the country is estimated to be far higher - at an estimated 200,000 daily infections on Monday - due to a time lag and because many cases are never picked up by the testing programme.

Hopkins said with so many people expected to contract the virus over the coming weeks, the NHS would come under significant pressure if only a fraction became ill enough to need hospital care.

"If we have a million infections a day, even a very small proportion of those individuals requiring hospitalisation will put a significant impact on healthcare," she told the Commons science and technology committee.

There are also concerns about the impact on schools, lorry drivers and shop workers if cases continue to rise rapidly while forcing 10 days' isolation for anyone who contracts Covid.

The warning came as Nicola Sturgeon urged Scots to limit indoor mixing to no more than three households over Christmas and reduce social contacts "as much as possible" in the coming weeks to help slow the spread of the variant.